The present invention relates to clutch apparatus capable of selectively connecting two drive shafts to a driven shaft, normally holding one drive shaft connected to the driven shaft and, when the latter is overloaded, connecting the other drive shaft to the driyen shaft. The clutch apparatus according to the invention finds a typical application in drive means for the infeed mechanism of a press.
An automatic press system is known which includes an infeed mechanism for successively feeding workpieces into the press proper in synchronism with the up-and-down movement of the slide carrying the upper die or punch. Drive means for the infeed mechanism and drive means for the press proper are interlocked for synchronizing them. It has also been known to provide, at the point of connection between the infeed drive means and the press drive means, a mechanism for preventing the former from being overloaded by the latter. When the torque being applied from the press drive means to the infeed drive means becomes so great that the infeed mechanism might be destroyed, the overload prevention mechanism functions to disconnect the press and the infeed drive means. So disconnected from the press drive means, the infeed drive means are powered from a separate drive source of smaller output torque totally independent of the press drive means.
An objection to the above description prior art is that the overload prevention mechanism and the drive source for the infeed mechanism have been provided separately, not structurally integrated. This of course is undesirable in view of the larger space requirement and the higher manufacturing cost.